P R E L I M I N A R Y
S6/LOCK/CLKDIV2/PIO29
TMRIN1/PIO0
Bus Cycle Status Bit 6 (output, synchronous)
Bus Lock (output, synchronous)
Clock Divide by 2 (input, internal pullup)
Timer Input 1 (input, synchronous, edge-sensitive)
This pin supplies a clock or control signal to the internal
microcontroller timer 1. After internally synchronizing a
Low-to-High transition on TMRIN1, the microcontroller
increments the timer. TMRIN1 must be tied High if not
being used. When PIO0 is enabled, TMRIN1 is pulled
High internally.
S6—During the second and remaining periods of a
cycle (t2, t3, and t4), this pin is asserted High to indicate
a DMA-initiated bus cycle. During a bus hold or reset
condition, S6 floats.
LOCK—This signal is asserted Low to indicate to other
system bus masters that they are not to gain control of
the system bus. This signal is only available during t1.
TMRIN1 is driven internally by INT2/INTA0/PWD when
pulse width demodulation mode is enabled. The
TMRIN1/PIO0 pin can be used as a PIO when pulse
width demodulation mode is enabled.
LOCK on the Am186ES and Am188ES
microcontrollers does not conform to the timing of the
LOCK signal on the 80C186/188 microcontrollers. This
signal is primarily intended for use by emulators.
TMROUT0/PIO10
Timer Output 0 (output, synchronous)
This pin supplies the system with either a single pulse
or a continuous waveform with a programmable duty
cycle. TMROUT0 is floated during a bus hold or reset.
CLKDIV2—If S6/CLKDIV2/PIO29 is held Low during
power-on reset, the chip enters clock divided by 2
mode where the processor clock is derived by dividing
the external clock input by 2. If this mode is selected,
the PLL is disabled. The pin is sampled on the rising
edge of RES.
TMROUT1/PIO1
Timer Output 1 (output, synchronous)
This pin supplies the system with either a single pulse
or a continuous waveform with a programmable duty
cycle. TMROUT1 floats during a bus hold or reset.
If S6 is to be used as PIO29 in input mode, the device
driving PIO29 must not drive the pin Low during power-
on reset. S6/CLKDIV2/PIO29 defaults to a PIO input
with pullup, so the pin does not need to be driven High
externally.
TXD0/PIO22
Transmit Data 0 (output, asynchronous)
This pin supplies asynchronous serial transmit data to
the system from serial port 0.
SRDY/PIO6
Synchronous Ready (input, synchronous,
level-sensitive)
TXD1/PIO27
This pin indicates to the microcontroller that the
addressed memory space or I/O device will complete a
data transfer. The SRDY pin accepts an active High
input synchronized to CLKOUTA.
Transmit Data 1 (output, asynchronous)
This pin supplies asynchronous serial transmit data to
the system from serial port 1.
UCS/ONCE1
Using SRDY instead of ARDY allows a relaxed system
timing because of the elimination of the one-half clock
period required to internally synchronize ARDY. To
always assert the ready condition to the
microcontroller, tie SRDY High. If the system does not
use SRDY, tie the pin Low to yield control to ARDY.
Upper Memory Chip Select (output, synchronous)
ONCE Mode Request 1 (input, internal pullup)
UCS—This pin indicates to the system that a memory
access is in progress to the upper memory block. The
base address and size of the upper memory block are
programmable up to 512 Kbytes. UCS is held High
during a bus hold condition.
TMRIN0/PIO11
Timer Input 0 (input, synchronous, edge-sensitive)
After reset, UCS is active for the 64 Kbyte memory
range from F0000h to FFFFFh, including the reset
address of FFFF0h.
This pin supplies a clock or control signal to the internal
microcontroller timer 0. After internally synchronizing a
Low-to-High transition on TMRIN0, the microcontroller
increments the timer. TMRIN0 must be tied High if not
being used. When PIO11 is enabled, TMRIN0 is pulled
High internally.
ONCE1—During reset, this pin and LCS/ONCE0 indi-
cate to the microcontroller the mode in which it should
operate. ONCE0 and ONCE1 are sampled on the ris-
ing edge of RES. If both pins are asserted Low, the mi-
crocontroller enters ONCE mode. Otherwise, it
operates normally. In ONCE mode, all pins assume a
high-impedance state and remain in that state until a
subsequent reset occurs. To guarantee that the micro-
TMRIN0 is driven internally by INT2/INTA0/PWD when
pulse width demodulation mode is enabled. The
TMRIN0/PIO11 pin can be used as a PIO when pulse
width demodulation mode is enabled.
36
Am186/188ES and Am186/188ESLV Microcontrollers
AMD [ AMD ]
